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Comparative Study
. 2017 May;31(3):221-232.
doi: 10.1111/ppe.12359. Epub 2017 Apr 18.

Newborn Length of Stay and Risk of Readmission

Free PMC article
Comparative Study

Newborn Length of Stay and Risk of Readmission

Katie Harron et al. Paediatr Perinat Epidemiol. .
Free PMC article


Background: Evidence on the association between newborn length of hospital stay (LOS) and risk of readmission is conflicting. We compared methods for modelling this relationship, by gestational age, using population-level hospital data on births in England between 2005-14.

Methods: The association between LOS and unplanned readmission within 30 days of postnatal discharge was explored using four approaches: (i) modelling hospital-level LOS and readmission rates; (ii) comparing trends over time in LOS and readmission; (iii) modelling individual LOS and adjusted risk of readmission; and (iv) instrumental variable analyses (hospital-level mean LOS and number of births on the same day).

Results: Of 4 667 827 babies, 5.2% were readmitted within 30 days. Aggregated data showed hospitals with longer mean LOS were not associated with lower readmission rates for vaginal (adjusted risk ratio (aRR) 0.87, 95% confidence interval (CI) 0.66, 1.13), or caesarean (aRR 0.89, 95% CI 0.72, 1.12) births. LOS fell by an average 2.0% per year for vaginal births and 3.4% for caesarean births, while readmission rates increased by 4.4 and 5.1% per year respectively. Approaches (iii) and (iv) indicated that longer LOS was associated with a reduced risk of readmission, but only for late preterm, vaginal births (34-36 completed weeks' gestation).

Conclusions: Longer newborn LOS may benefit late preterm babies, possibly due to increased medical or psychosocial support for those at greater risk of potentially preventable readmissions after birth. Research based on observational data to evaluate relationships between LOS and readmission should use methods to reduce the impact of unmeasured confounding.

Keywords: Caesarean delivery; hospital records; length of stay; patient readmission; preterm delivery.


Figure 1
Figure 1
Distribution of newborn length of stay for babies in the study population, by gestational age (full term, 39 +  completed weeks’; early term, 37–38 completed weeks’; late preterm, 34–36 completed weeks’).
Figure 2
Figure 2
Relationship between the percentage of babies with one or more unplanned readmissions and newborn LOS, by gestational age (full term, 39 +  completed weeks’; early term, 37–38 completed weeks’; late preterm, 34–36 completed weeks’). Symbols represent observed values, and line represents model values. The percentage of caesarean births with a newborn LOS of 0 days was very small (0.4%), but this category has been included for completeness.
Figure 3
Figure 3
Risk of readmission and ratio of observed/expected LOS by method of delivery (vaginal = squares; caesarean = circles) and gestational age (full term, 39 +  completed weeks’; early term, 37–38 completed weeks’; late preterm, 34–36 completed weeks’). Expected LOS ratio = 0.77–1.13; shorter than expected LOS ratio = 0.00–0.77; longer than expected LOS ratio = 1.13–7.26.

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